Emma,
It suggests that you have the wrong Keyboard layout set.
To change this to the correct layout for your country, I am guessing United Kingdom, follow these steps.
1) Click on launch bar on your desktop
2) Click preferences
3) Click desktop preferences
4) Click Keyboard
5) Click Behaviour
Then when the keyboard behaviour window opens, select Layouts at the top.
Then change the selected layout to the country you require. For example, "United Kingdom".
Hope this helps.
Paul